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Let's consider this passage in context:
Hebrews 12:1-4 Therefore we also, since we are surrounded by so great a cloud of witnesses, let us lay aside every weight, and the sin which so easily ensnares us, and let us run with endurance the race that is set before us, 2 looking unto Jesus, the author and finisher of our faith, who for the joy that was set before Him endured the cross, despising the shame, and has sat down at the right hand of the throne of God. 3 For consider Him who endured such hostility from sinners against Himself, lest you become weary and discouraged in your souls. 4 You have not yet resisted to bloodshed, striving against sin.
Clearly then, verse 4 means that we are engaged in constant war against sin. We have a wonderful hope to motivate us in that battle. Any sacrifice is worth the end result, eternal life, that God will provide to those who remain faithful. Jesus gave his life in that struggle so that we might have the opportunity of life. In our struggle against sin, we have not resisted to the point of shedding our blood as he did!
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